Rainbow Electronics AT91CAP9S250A - Manual (Page 151)

151
6264A–CAP–21-May-07
AT91CAP9S500A/AT91CAP9S250A
21.5.8.1 I/O Mode, Common Memory Mode, Attribute Memory Mode and True IDE Mode
Within the NCS4 and/or NCS5 address space, the current transfer address is used to distin-
guish I/O mode, common memory mode, attribute memory mode and True IDE mode.
The different modes are accessed through a specific memory mapping as illustrated on Figure
21-2 . A[23:21] bits of the transfer address are used to select the desired mode as described in
Table 21-4 on page 151 .
Figure 21-2. CompactFlash Memory Mapping
Note: The A22 pin is used to drive the REG signal of the CompactFlash Device (except in True IDE
mode).
21.5.8.2 CFCE1 and CFCE2 Signals
To cover all types of access, the SMC must be alternatively set to drive 8-bit data bus or 16-bit
data bus. The odd byte access on the D[7:0] bus is only possible when the SMC is configured
to drive 8-bit memory devices on the corresponding NCS pin (NCS4 or NCS5). The Chip
Select Register (DBW field in the corresponding Chip Select Register) of the NCS4 and/or
NCS5 address space must be set as shown in
Table 21-5 to enable the required access type.
NBS1 and NBS0 are the byte selection signals from SMC and are available when the SMC is
set in Byte Select mode on the corresponding Chip Select.
CF Address Space
Attribute Memory Mode Space
Common Memory Mode Space
I/O Mode Space
True IDE Mode Space
True IDE Alternate Mode Space
Offset 0x00E0 0000
Offset 0x00C0 0000
Offset 0x0080 0000
Offset 0x0040 0000
Offset 0x0000 0000
Table 21-4. CompactFlash Mode Selection
A[23:21] Mode Base Address
000 Attribute Memory
010 Common Memory
100 I/O Mode
110 True IDE Mode
111 Alternate True IDE Mode